Flexible and Adaptable Buffer Management Techniques for Database Management Systems

The problem of buuer management in database management systems is concerned with the eecient main memory allocation and management for answering database queries. Previous works on buuer allocation are based either exclusively on the availability of buuers at runtime or on the access patterns of queries. In this paper, we rst propose a uniied approach for buuer allocation in which both of these considerations are taken into account. Our approach is based on the notion of marginal gains which specify the expected reduction in page faults by allocating extra buuers to a query. Then, we extend this approach to support adaptable buuer allocation. An adaptable buuer allocation algorithm automatically optimizes itself for the speciic query workload. To achieve this adaptability, we propose using run-time information, such as the load of the system, in buuer allocation decisions. Our approach is to use a simple queueing model to predict whether a buuer allocation will improve the performance of the system. Thus, this paper provides a more theoretical basis for buuer allocation. Simulation results show that our methods based on marginal gains and our predictive methods consistently outperform existing allocation strategies. In addition, the predictive methods have the added advantage of adjusting their allocation to changing workloads.